Further to my recent post; I think I am clearer as to the strange support given to the stupid idea that the modern Left are the new 'puritans': it seems that Catholics (Roman, Anglo, perhaps Orthodox) are using the argument as a way of refighting the Reformation.
The core problem with the Left=Puritan argument is that it puts politics above Christianity; in that it implicitly argues that political expediency ought to be primary in deciding the nature of Christianity.
In other words, the implicit assumption is that Christianity is to be understood as a part of The State, and in terms of how best a nation may be governed.
The Left=Puritan idea is a way of reasserting either the ideal of the Constantine/ Byzantine/ Anglican synthesis of Roman State and the Christian Church; or the Medieval 'City of Man'-'City of God' separate-realms division between the King and the Pope. Implicitly, the core question being addressed is the problem of how Christianity may function in the administration of a stable state.
This is understandable among members of the 'secular-Right' who regard religion as a means to an end; and therefore hate and fear serious, zealous, primarily motivating Christianity; they prefer a tolerant, insipid, 'Sunday' Christianity of reasonable men and moderation - something that fits smoothly into the Establishment.
But such a style of argument ought to be regarded as abhorrent by serious Catholic Christians; those who put their religion above politics... yet such people are in fact making this argument; whether by error or confusion, or from falling into sin. They ought to be giving credit for serious Christian faith as more important than political expediency; but have fallen into putting expediency first.
Such a view equates 'puritans' with the political perils that ensue when individual Man is in a personal relationship with Jesus, or God the Father. So, it is a re-run of one aspect of the Reformation; which was between serious Christians (mostly of lower and middling classes) and the Establishment supporters of the political expediency of moderation and corruption.
So the equation is made between the destabilising effects of zeal and enthusiasm - or personal religion; and what are assumed to be similar defects in the modern New Left. (This is, anyway, not what I personally see among modern Leftists - who seem to be mostly timid bureaucrats rather than wild zealots, but that is aside.)
The fault is that this is to equate Christian zeal (even if erroneous in one way or another) with political zeal. It is, in fact, to see Christianity in terms of politics. Examine the arguments, and you will see that this is so.
Further, I think those who use modern Leftism to excoriate what they suppose to be puritanism are making a rhetorical mistake if they suppose that an argument in favour of the moderate corruption and reasonableness of a mature and stable Byzantine or Holy Roman monarchy will inspire and fire the individual idealism and courage necessary to roll-back the New Left.
Given the ubiquity and degree of top-down corruption (mainly politicization) in the Catholic (and other mainstream) churches; the only possible future of Christianity in the West is to be strong, personal and primary.
And for such Christians to set-aside the political wrangles, and especially arguments about political expediency, until after Western Men has recovered (or generated anew) a living, inspiring, motivating Christian faith.